Steam power plant



July 10, 1945. A. DOBLE STEAM POWER PLANT Filed May 22, 1944 2 Sheets-Sheet 1 fwenzor A bnerLDo 6 la ,BY wmv/mflw I fflor July 10, 1945.

A. DOBLE STEAM POWER PLANT Filed May 22, 1944 2 Sheets-Sheet 2' Patented July 10, 1945 Abner Doble, Chicago, Ill'.,

assignor to Stanley Steam Motors Corporation, Chicago, 111., a corporation of Delaware Application May 22, 1944, Serial No. 536,658

12 Claims.

This invention relates to power plants employing elastic fluids or vapors such as steam, more particularly to steam power plants of small size but large capacity installed in automotive vehicles, such as busses, for propelling vehicles, and the invention has for an object the provision of improved power plants of this character of minimum size and weight which operate at high efllciencies.

In power plants previously proposed for steam vehicles, a heater or boiler of the tube or flash type has been employed in which the heat is supplied by burning a mixture of fuel and air provided by blowing air through a suitable carburetion device. Steam from the boiler is supplied to a steam engine for propelling the vehicle, and in order that the quantity of steam supplied by the boiler may increase automatically,

substantially in accordance with increasing demands of the engine under various speed and load conditions, an exhaust steam turbine has been provided for driving various auxiliaries including the blower which supplies the air to the burner. As the heat supplied to the boiler is increased, it is of course necessary, in order to maintain the desired quality of the steam, to supply feed water to the boiler in increasing quantities, and it has heretofore been proposed to employ a feed water pump of sufflcient capacity to supply the boiler under maximum demands for steam and to control the operation of the feed water pump in accordance'with boiler conditions.

Since the amount of feed water required by the boiler under conditions of minimum steam demands, such as light loads and low speeds, is only a small percentage of the total capacity of a feed water pump capable of supplying'the boiler under maximum steam demands, such a large capacity pump will be idle for long periods of time during operation of the power plant, and while it is uneconomical to provide such a large pump, the total capacity of which is necessary only under occasionally encountered conditions, reduction of the size of the pump may result in an insufficient supply of steam under maximum demand conditions. It is, a further 1 to supply feed water to the boiler, a pair of feed a K water pumps is provided connected to be driven by the steam engine, the connection for one of the pumps including an overrunning clutch which permits the one pump to be overdriven relative to the engine. A drivingconnection is provided between this one pump and the exhaust turbine, so that this pump is driven by the engine when the turbine is operating below a predetermined speed and is driven by the turbine when the turbine operates at higher speeds. The turbine-driven pump is of relatively small size and has a feed watercapacity less than the boiler capacity at various loads and speeds, but the total capacity of the two feed water pumps exceeds the boiler capacity over a substantial portion of the entire range of operation.

In order to control automatically the amount of feed water supplied to the-boiler in accordance with the demands for, steam, temperatureresponsive means associated with the boiler are provided for rendering the engine-driven pump selectively operative or inoperative to supply feed water, and thus the supply 'of feed water from the turbine-driven pump is selectively augmented in accordance with boiler temperature conditions.

I In addition, means responsive to boilerepressure object of the invention, therefore, to provide im- V proved feed water pump means for steam plants are provided for rendering both pumps inoperative if the boiler pressure increases beyond the predetermined value.

For a more complete understanding of the invention, reference should now be had to the drawings in which:

Fig. 1 isa somewhat diagrammatic illustration of a steam power plant embodying the present invention, certain parts of the installation and the control means therefor being omitted in order to simplify the drawings;

Fig. 2 is a diagrammatic view illustrating one type of pump control means which may be employed in carrying out the invention; and;

Figs. 3 and 4 are diagrams illustrating the operation of the power plant and the feed water pumps under light load and full load conditions respectively.

Referring now to the drawings, the inventio is illustrated in Fig. 1 as embodied in a powen particularly applicable to, and it will be described of the turbine being connected by a steam conduit I1 to a feed water heater l8. From the feed water heater Hi the steam passes through a conduit l9 to suitable condensing means (not shown), and the condensate from the condensing means is delivered to a hot well indicated diagrammatically in the drawings and identified by v the reference umeral 20.

Associated 'th the engine l4 and the exhaust turbine I6 i a pair of feed water pumps 2| and 22 which w' lbe more fully described hereinafter, and as sho n in Fig. l the respective intake sides of the pu ps 2| and 22 are connected by suitable conduits 23 and 24 to a common conduit 25 through which feed water may be drawn from the hot well by the pumps. The discharge sides of the respective pumps are connected through suitable discharge conduits 26 and 21 to a common discharge conduit 28, through which feed water is conducted by way of a coil 29 in the feed water heater l8 and a conduit 30 to the boiler H1. The boiler l0, which is illustrated diagrammatically in the drawings, is of a type well known in the 'art and includes a long tube 3| through which the water passes as it is heated and converted into steam, the discharge end of the tube 3| being connected to the steam conduit leading to the throttle as previously described. Only so much of the tube 3| is shown as is necessary to illustrate the association with the boiler of the thermostatic control means to be hereinafter described.

Heat is supplied to the boiler I9 by injecting into the fire box of the boiler an inflammable mixture which is created by blowing a current of air through a venturi 32, at the throat portion of which is located a carburetion device 33 containing a quantity of fuel. A spark plug 34 serves to ignite the inflammable mixture and the air is supplied by a suitable blower 35 which, as indicated diagrammatically by the broken line 36, is adapted to be driven from the auxiliary or exhaust steam turbine l6, and/or by an electric motor 90 as will be more fully described hereinafter.

The feed water pump 2| is connected in any suitable manner for direct drive by the engine I4, and the pump 22 is connected, preferably through suitable gearing 31, to the shaft of the exhaust turbine I6. In addition, the pumps 2| and 22 are connected together through an'overrunning clutch which may be of any suitable type well known in the art, and which is arranged so that the pump 22 will be driven by the engine Hi When the turbine I6 is operating below predetermined speeds and so that the pump 22 will be driven by the turbine I6 when the turbine operates at higher speeds.

Although the pumps 2| and 22 may be of any suitable type well known in the art having valve or other means operable selectively to render the pumps operative or inoperative to supply feed water, the pump 2| is illustrated diagrammatically in Fig. 2 as comprising a piston 38 adapted served that when the piston 38 reciprocates, feedwater will .be drawn in through the intake conduit 23 and the valve 40, and will be discharged from the cylinder 39 through the discharge valve 4| and the discharge conduit 24 on the return stroke of the piston 38. When the electromagnet 45 is deenergized, the plunger 44 returns to theposition illustrated in Fig. 2 so as positively to hold theintake ball valve 46 ofi of the seat 42, and so long as the valve is thus held by the plunger 44 reciprocation of thepiston will be ineffective to discharge feed water through the exhaust valve 4|. It will be understood that the pump 22 is similar in construction to the pump 2|, and is provided with a suitable electromagnet 46 for controlling the valve means so as selectively to render the pump 22 operative or inoperative to pump feed water.

In accordance with the present invention the pump 2| is adapted selectively to be rendered operative and inoperative in accordance with boiler temperatures, and accordingly there is provided a suitable thermostatic means associated with the boiler for controlling the electromagnet 45 of the pump 2|. The thermostatic means, as shown in the drawings, is of a type well known in the art and comprises an expansible heat-responsive tube 41 which is positioned within a portion 48 of the boiler tube 3|, the inner end of the tube 41 being connected to an operating rod 49, the outer end of which is pivotally connected, as shown, to a centrally pivoted arm 50. The arm 58 is provided adjacent its lower end with a finger 5| adapted to engage a pivoted contact arm 52 which is arranged to make contact with a stationary contact 53. Similarly, the upper end of the arm 56 is provided with a finger 54 adapted to engage a pivoted contact arm 55 which cooperates with a stationary contact 56.

In the drawings, the thermostatic means and the associated contacts are shown in a neutral or normal position wherein the contacts 52, 53 and 55, 56 are both closed. Upon an increase in temperature within the boiler I0, the tube 41 will increase in length so as to move the operating rod 49 in a right-hand direction, whereupon the lever 50 will pivot in a counterclockwise direction from the direction shown in the drawings, so as to openfcontacts 55, 56. Upon a decrease in the temperature in the boiler, the tube 41 contracts, moving the rod 49 in a left-hand direction and causing the pivoted lever 50 to move in a clockwise direction about its pivot so as to open the contacts 52, 53.

Associated with the steam conduit through which steam is conducted from the boiler ID to the engine I4, is a pressure-responsive device 51 which is arranged, as shown, to open a pair of contacts 58 whenever the steam pressure exceeds a predetermined maximum value. c As shown in the drawings, current for energizing the electromagnets 45, 46 of the pumps 2| and 22, respectively, is supplied from a suitable source of current represented by a battery 59, one side of which is connected through a conductor 60 to the contacts 58 of the pressure-responsive device 51.

'The energizing circuit for the electromagnet 46 of the pump 22 may be traced from one side of the battery 59 through the conductor 60, the contacts 58 and the conductors 6|, 62 and 63, to one side of pump2| extends from the I ing 31, so as to drive,

suitable ground connections.

64. Thus it will be seen that so long as the steam pressure is below a predetermined value, the electromagnet 46 on the pump 22 will be energized and the pump 22 will be operative tofsupply feed water to the boiler. l

The circuit for the electromagnet 45 of the battery through the conductor 60. the contacts 68, the conductors BI and 62, and by way of the conductor 66 to the contact 52 of the thermostatic meansresponsive to the boiler temperature. From the cooperating contact 53 the circuit may be traced through a conductor 66 to the electromagnet 45, which is likewise provided with a suitable ground connection 64. Thus it will be seen that so long as the boiler temperature exceeds a predetermined value and the steam-pressure is below a predetermined value, the pump 2| will likewise be operative to supply feed water to the boiler, the total amount of feed water being supplied constituting the sum of the pump capacities. However, when the temperature of the boiler decreases below a predetermined value, the circuit for the magnet 45 of the pump 2| will be opened by separation of the contacts 52 and 53 and the pump 2| will be rendered inoperative to supply feed water in the manner heretofore described in connection with Fig. 2.

Since the energizing circuits for both of the electromagnets 45 and 46 include the contacts 58 of the pressure-responsive means 51, it will be apparent that both electromagnets will be deenergized to render the pumps 2| and 22 inoperative whenever the boiler pressure exceeds a predeterminedv value.

When the engine I4 is operating at light loads, the exhaust turbine l8 does substantially no useful work and the turbine rotor merely floats or rotates freely, being driven by the engine |4 through the clutch 15, the pump 22 and the gearthe blower 35 at speeds directly proportional to the speed of the engine. The boiler capacity is of course proportional to the speed of the blower 35, but it has been found that if the blower speed is allowed to drop below a predetermined minimum, difficulties will be encountered due to uneven fire, fluctuating drafts, etc. Accordingly, in power plants of this character, it is desirable to provide auxiliary draft means, such for example as an electric motor driving the blower 35 to prevent the draft or flow of air to the burner from decreasing below a predetermined minimum. This auxiliary draft means is shown in Fig. 1 of the drawings as an electric motor 90 connected to the shaft of the turbine, indicated by the broken line 36, and havthe point 12.

. ;"water capacities of the pumps 2 the engineer vehicle speed atlight loads is represented by the sloping line 10, and the broken line H, which intersects the line 10 at the point 12, represents the minimum boiler capacity maintained-by--the auxiliary draft meansat speeds below a,,predetermined speed corresponding to The sloping lines l3 and 14, re- 'spectively, represent the relation of the feed and 22 to the vehicle or engine speed at light loads, both pumps being driven by the engine l4 since the turbine B is not overdriving, and the line 16 in Fig.3 represents the feed water capacity of the two pumps.

It will b observed that at all speeds below a speed corresponding to the point 11, at which point the feed water pump capacity line 16 crosses the minimum bOiler capacity line H, the two pumps 2| and 22 are incapable of supplying sufl'lcient feed 'water' for the boiler if the burner operates continuously. However, at such low speeds under light load conditions it is not necessary for the burner to operate continuously in order to supply the desired amount of steam, and proper control of the burneris achieved through the contacts 55, 56 of the boiler temperatureresponsive means. Thus, whenever the amount of feed water supplied to th boiler by the pumps 2| and 22 is insuflicient, the temperature of the steam generated in the boiler increases and the temperature-responsive tube 41 increases in length so as to open the contacts 55, 56 and shut down the burner and auxiliary draft means when a predetermined boiler temperature is reached. The control circuits for the magnets 45 and 46 of the feed water pumps 2| and 22, however, are maintained closed through the contacts 52, 53 and both pumps thus continue to supply feed water to the boiler, thereby causing the boiler temperature to decrease, and at a predetermined boiler temperature the contacts 55, 56 close to initiate again the operation of the auxiliary draft means and the burner.

At vehicle or engine speeds above the minimum speed represented by the point 17 in Fig. 3. the total feed water capacity of the pumps 2| and 22 represented by the line 16 exceeds th boiler capacity represented by the line 10. Supplying an excess quantity of feed water to the boiler causes the boiler temperature to decrease, and accordingly the contacts 52, 53 willbe opened at a predetermined boiler temperature to de-energize the electromagnet 45 and render the pump ing its energizing circuit controlled through the temperature-responsive contacts 55, 56 by way of a conductor 9|. An overrunning clutch 92 is disposed between the turbine I6 and the motor 90 so i as to permit the motor 90 to drive the blower 35 when the speed of the turbine shaft falls below a predetermined minimum. At turbine shaft speedsabove this minimum, the motor 90 is overdriven and consequently the current drawn by the motor decreases to a minimum as the blower speed rises. The usual burner control means for the spark plugs, dampers, etc., are likewise controlled in accordance with the boiler temperature conditions through a conductor 93 and the previously referred to contacts 55, 56 of the temperature-responsive means.

In Fig. 3 the relation of the boiler capacity to 2| inoperative. The pump 22, however, continues to supply feed water to the boiler, but since the capacity of the pump 22 alone is less than the boiler capacity at all speeds of operation, the temperature of the boiler will increase due to the insufficient supply of feed water until closure of the contacts 52, 53 is effected to render the pump 2| operative again. Accordingly, the amount of feed water supplied to the boiler by the pumps 2| and 22 is varied automatically between th minimum and maximum values represented by the lines 74 and 16 at any particular speed of operation, so as to supply to the boiler an average amount of feed water corresponding to the boiler under full load at various speeds are represented in a manner similar to the representation in Fig. 3. It will be observed that the capacity of the engine-driven pump 2| is represented in Fig. 4 by the same line, 13, as appears in Fig. 3, since the capacity of this pump is affected only by the speed of th engine and is independent of load conditions. The capacity of the turbine pump 22, which as indicated is now being overdriven at speeds gree ter than the driving speed of the engine, is represented in Fig. 4 by the line I8, and the boiler capacity at full load is represented in Fig. 4 by the line 19.

It will be observed that the capacity of the turbine-driven pump 22 and the boiler capacity increase quickly as the speed of the engine increases to a point of maximum capacity and then become substantially constant for higher speeds. The combined capacity of the pumps 2| and 22 is represented in Fig. 4 by the line 80, and it will be observed that the combined capacity of the two pumps under full load conditions is greater than the boiler capacity at all except very low speeds, the broken line 1| in Fig. 4 again representing the minimum boiler capacity maintained by the auxiliary draft means. Since the capacity of the turbine-driven pump 22, represented by the line 18, is less than the boiler capacity rep resented by the line 19, the temperature control means associated with the boiler will be operated automatically in accordance with boiler temperature conditions selectively to render the engine pump 2| operative or inoperative, so that amounts of feed water being supplied to the boiler varies between the lines 18 and 80 and an average amount of feed water corresponding to the boiler capacity is thereby supplied, as previously described in connection with the light load condition represented by Fig. 3. In other words, the turbine pump operates continuously to supply an insufficient amount of feed water to the boiler,

and the engine-driven pump 2| is selectively rendered operative and inoperative to augment the supply of feed water so as to maintain an average supply of feed water corresponding to the boiler capacity.

At speeds below the speed represented by the I point 8| at which the line 1| intersects the line 80, the contacts 55, 56 will function to shut down the burner whenever the boiler temperature rises due to an insufiicient supply of feed water, as described in connection with the light load, low speed zone of operation represented by the portion of Fig. 3 to the left of the point I1.

It will be understood that under intermediate load conditions the capacity of the turbine pump 22 will be represented by lines intermediate the line 14 of Fig. 3 and the line 18 of Fig. 4, and the boiler capacity may similarly be represented by lines intermediate the line 10 of Fig. 3 and the line 19 of Fig. 4. By providing a plurality of small pump units, one of which is continuously operative and the other of which is selectively rendered operative and inoperative to augment the supply of the continuously operative pump, a lightweight economical feed water system is provided which avoids large heavy pumps which may operate for only short periods under various load conditions. Consequently, an increase in efficiency and reduction of bulk and weight is obtained.

While only one engine-driven pump 2| and one turbine-driven pump 22 have been illustrated and described, it will be understood that any number or small pumps may be provided, and in one physical embodiment or the invention it was found advantageous to employ four pumps, two of which were driven by the engine alone and the other two or which were adapted to be driven selectively by the engine or the turbine, depending upon the load and/or speed of operation.

To summarize the operation of the power plant shown in the drawings, it will be apparent that if at any condition of speed or load the amount of feed water supplied to the boiler by the pump 22 is insufllcient to satisfy the demands of the boiler, the boiler temperature will rise and the contacts 52, 58 of the boiler temperature-responsive means will close to render the engine-driven pump 2| operative and increase the supply of feed water. If the feed water thus supplied is sufiicient or in excess of the demands of the boiler, the contacts 52, 53 will remain closed only so long as the boiler temperature remains above a predetermined desired temperature, and the pump 2| will thus selectively be rendered operative and inoperative to insure the required or optimum supply of feed water.

If on the other hand the total amount of feed water supplied by the pumps 2| and 22 is insufiicient to satisfy the demands of the boiler, as it will be at very low speeds, the temperature of the boiler will continue to increase until the contacts 55, 56 are opened to shut down the burner. When the burner is shut down the feedwater pumps continue to operate until the boiler temperature is brought back to the desired value, whereupon the operation will proceed with the burner being selectively cut in and out of service in accordance with the boiler temperature conditions. If at any time during operation of the power plant the steam pressure exceeds a predetermined maximum value, the pressure-responsive means 51 will operate to open the contacts 58 and-thereby not only render both the pumps 2| and 22 ineifective, but also shut downthe burner, the energizing circuits for which extend through the contacts 58 as well as through the contacts 55, 56.

While I have shown particular embodiments of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit andscope of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A steam power plant comprising ,a boiler, a pair of prime movers operable by steam generated in said boiler, a pair of feed-water pumps for selectively driving one of said pumps from one or the other of said prime movers depending upon the relative speeds of said prime movers, means for driving the other of said pumps solely from one of said prime movers, and means responsive to a condition in said boiler for rendering said other pump selectively operative 01 inoperative to supply feed water to said boiler.

asvasev pair of prime movers operable by steam generated in said boiler, a pair of feed-water pumps for supplying feed water to said boiler, means in cluding clutch means for selectively driving one of said pumps from one or the other of said prime movers depending upon the relative speeds of said prime movers, means for driving the other of said pumps solely from one of said prime movers, and means responsive to boiler temperature conditions for rendering said other pumpselectively operative or inoperative to supply feed water to said boiler.

4. A steam power plant comprising a boiler, a pair of prime movers operable by steam generated in said boiler, a pairof feed-water pumps for supplying feed water to said boiler, means including clutch means for selectively driving one of said pumps from one or the other of said prime movers depending upon the relative speeds of said prime movers, means for driving the other of said pumps solely from one of said prime movers, control means associated with each of said pumps for rendering the respective pumps operative or inoperative to supply feed water to said boiler, means responsive to a condition in said boiler for operating said control means selectively to render said other pump operative or inoperative, and means responsive to a second boiler condition for operating said control means to render both or said pumps inoperative.

5. A steam power plant comprising aboiler, a pair of prime movers operable by steam generated in said boiler, a pair of feed-water pumps for supplying feed water to said boiler, means including clutch means for selectively driving one of said pumps from one or the other of said prime movers depending upon the relative speeds of said prime movers, means for driving the other of said pumps solely from one of said prime movers, control means tor each pump operable to render the respective pumps operative or inoperative to supply feed water to said boiler, means responsive to boiler temperature conditions for operating said control means selectively to render said other pump operative or inoperative whereby the amount oi feed water supplied by said pumps is controlled in accordance with said boiler temperature conditions, and means responsive to boiler pressure for operating said control means to render both of said pumps inoperative when the boiler pressure exceeds a predetermined value.

6. A steam power plant comprising a boiler, a

pair 01 prime movers operable by steam generated in said boiler, a plurality of feed-water pumps for supplying feed water to said boiler, means for driving all or said pumps by one of said prime movers when the driving speed of said one prime mover is higher than the driving speed of the other prime mover, said driving means for one oi said pumps including an overrunning clutch permitting said one pump to be driven at speeds higher than the driving speed of said one prime mover, means for driving said one pump by said other prime mover at said higher speeds, and means responsive to boiler temperature conditions for rendering another or said pumps operative or inoperative to supply feed water to said boiler, whereby the quantity of feed water supplied to said boiler by said pumps is controlled in accordance with boiler temperature conditions.

'7. A steam power plant comprising a boiler, a first prime mover operable by steam supplied from said boiler, an auxiliary prime mover operable by exhaust steam from saidiirst prime mover whereby thespeed or said auxiliary prime mover varies with the load on saidfirst prime mover, a plurality of feed-water pumps for supplying feed water to said boiler, "means for driving all of said pumps by said first prime mover, saidodriving means for one of said pumps includ- ,jffg an overrunning clutch Permitti Said one pump to be driven at speeds higher than the driving speed of said first prime mover, means connecting said one pump for drive by said auxiliary prime mover at said higher speeds whereby said one pump is driven by said first prime mover under light loads and by said auxiliary prime mover at heavy loads, the other of said pumps being driven by said first prime mover under all load conditions, and means responsive to boiler temperature conditions for rendering said other pump operative or inoperative to supply feed water to said boiler, whereby said other pump is rendered selectively operative to augment the quantity of feed water supplied to said boiler by said one pump.

8. A power plant comprising a boiler, a prime moveroperable by steam generated in said boiler, an""auxiliary turbine operable by exhaust steam from said prime mover, means driven by said turbine for varying the steam generating capacity of said boiler in accordance with the load on said prime mover and the speed of operation. of said prime mover,-a pair of feed-water pumps for supplying feed water to said boiler, means for driving said pumps by said prime mover when the driving speed of said prime mover exceeds the driving speed of said turbine, said driving means for one of said pumps including overrunning clutch means, means for driving said one pump by said turbine when the driving speed of said turbine exceeds the driving speed of said engine whereby the feed-water capacity of said one pump varies with the load on said prime mover and the speed of operation of said prime mover,

the capacity of said one pump being less than the bine for driving said blower, means for supplying exhaust steam from said engine to said turbine whereby the operation of said blower and the steam generating capacity of said boiler vary with the load and speed of said engine, a pair of feed-water pumps for said boiler, means for selectively driving one of said pumps from said engine or said turbine depending upon th relative speeds of said engine and turbine, and means for driving the other of said pumps solely from said engine.

10. A steam power plant comprising a steam engine, a boiler for supplying steam to said engine, a burner for said boiler, a blower :tor iurnishing combustion air to said burner; auxiliary turbine for driving said blower, for

, supplying exhaust steam from said engine to said turbine whereby the operation of said blower and the steam generating capacity of said boiler vary with the load and speed of said engine, a pair of rendering feed-water pumps for said boiler, means for selectively driving one of said, pumps from said engine or said turbine depending upon the relative speeds of said engine and turbine, means for driving the other of said pumps solely from said engine, and means for rendering said other pump selectively operative or inoperative to supply feed water to said boiler.

11. Asteam power plant comprising a steam engine, a boiler for supplying steam to said engine, a burner for said boiler, a blower for furnishing combustion air to said burner, an auxiliary turbine for driving said blower, means for supplying exhaust steam from said engine to said turbine whereby the operation of said blower and the steam generating capacity of said boiler vary with the load and speed of said engine, a pair of feed-water pumps for said boiler, means including clutch means for driving one of said pumps selectively from said engine or said turbine depending upon th relative speeds of said engine and turbine, means for driving the other of said pumps solely from said engine, and means responsive to boiler temperature conditions for said other pump selectively operative or inoperative whereby the quantity of feed water'supplied by said pumps is varied in accordance with boiler temperature conditions.

12. A steam power plant comprising a steam engine, a'boiler for supplyin steam to said engine, a burner -for said boiler, a blower for furnishing combustion air to said burner, an auxiliaryturbine for driving said blower, means for supplying exhaust steam from said engine to said turbine whereby the operation of said blower and the steam generating capacity of said boiler vary with the load and speed of said engine, a pair of feed-water pumps for said boiler, means including an overruning clutch for driving one of said pumps selectively from said engine or said turbine depending upon the relative speeds of said engine and turbine, means for driving the other of said pumps solely from said engine, means responsive to boiler temperature conditions for rendering said other pump selectively operative or inoperative whereby the quantity of feed water supplied by said pumps is varied in accordance with the boiler temperature conditions, and means responsive to boiler pressure for rendering both of said pumps inoperativ when the boiler pressure exceeds a predetermined value.

ABNER DOBLE. 

